Apache2

as I could see in the log, apache2 is restarting randomly... is this a normal behavior? does it affect the clients that are seeing web pages in that moment? how can I debug this in order to know WHO or WHAT is restarting apache2?

Some directions would be great for me, right now, I think I will have to check every log in my server... but I am a little blind with this... could some one check for similiar behavior in your own logs and see if this is happening only to me? thanks!